Equally Efficient Perovskite Solar Cells and Modules Fabricated via N‐Ethyl‐2‐Pyrrolidone Optimized Vacuum‐Flash

Abstract Efficiency reduction in perovskite solar cells (PSCs) during the magnification procedure significantly hampers commercialization. Vacuum‐flash (VF) has emerged as a promising method to fabricate PSCs with consistent efficiency across scales. However, the slower solvent removal rate of VF compared to the anti‐solvent method leads to perovskite films with buried defects. Thus, this work employs low‐toxic Lewis base ligand solvent N‐ethyl‐2‐pyrrolidone (NEP) to improve the nucleation process of perovskite films. NEP, with a mechanism similar to that of N‐methyl‐2‐pyrrolidone in FA‐based perovskite formation, enhances the solvent removal speed owing to its lower coordination ability. Based on this strategy, p – i –n PSCs with an optimized interface attain a power conversion efficiency (PCE) of 24.19% on an area of 0.08 cm 2 . The same nucleation process enables perovskite solar modules (PSMs) to achieve a certified PCE of 23.28% on an aperture area of 22.96 cm 2 , with a high geometric fill factor of 97%, ensuring nearly identical active area PCE (24%) in PSMs as in PSCs. This strategy highlights the potential of NEP as a ligand solvent choice for the commercialization of PSCs.